Atypical X-axis skipping problem (solved!)

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clayinmn
Posts: 4
Joined: Thu Jun 25, 2015 4:17 pm

Atypical X-axis skipping problem (solved!)

Post by clayinmn » Thu Jun 25, 2015 5:00 pm

Hello MakerGear friends,

First off, I just want to say that the M2 is amazing, this coming from a guy who owns two wooden PrintrBots... simply amazing.

Now I was hoping someone could help diagnose an X-axis skipping issue I've had. I have installed a dual extruder upgrade on this M2 and it prints great 70% of the time with no problems.
Occasionally, it will randomly skip on the X axis and move about a millimeter or two left on the X and print like that for the entire print. it has ruined a lot of long prints for me already.
[See image of globe]

After doing a lot of searching on the fourms (because thats usually where I go to fix my printrbots when something like this happens) I concluded that the problem must have been some variation of acceleration settings being too high and the increased mass on the printhead may have exaggerated that. So I went into settings and at this point I've decreased them to 1000 mm/min and tweaked a few things in the firmware like this:

Code: Select all


#define NUM_AXIS 4 // The axis order in all axis related arrays is X, Y, Z, E
#define HOMING_FEEDRATE {50*60, 50*60, 25*60, 0}  // set the homing speeds (mm/min)

#define DEFAULT_AXIS_STEPS_PER_UNIT   {44.44*2,44.44*2,200*2,471.5}  // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE          {500, 500, 25, 25}    // (mm/sec)
#define DEFAULT_MAX_ACCELERATION      {1000,1000,30,10000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION          1000    // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION  1000   // X, Y, Z and E max acceleration in mm/s^2 for retracts

 #define EXTRUDER_OFFSET_X {0.0, 31.15} // (in mm) for each extruder, offset of the hotend on the X axis
 #define EXTRUDER_OFFSET_Y {0.0, 0.0}  // (in mm) for each extruder, offset of the hotend on the Y axis

#define DEFAULT_XYJERK                20.0    // (mm/sec)
#define DEFAULT_ZJERK                 0.4     // (mm/sec)
#define DEFAULT_EJERK                 5.0    // (mm/sec)
However, this didn't seem to fix the problem, so I thought that maybe I was just crazy and one of the heads was dragging on the prints every so often.
So I re-tensioned the X belt and added a physical Z retraction step in the code (I use Slic3r and Repetier, but i tried this on Simplify3D and the problem still occured).

Still didn't fix it.

So, I programmed it to home X and Y each layer change and I printed out two parts to the Nautilus gears from thingiverse.
And the result:
When it got to the two pillars that are on the section that attaches two of the gears It reproduced this skipping effect EACH LAYER during the return from home.

[See other Image]

I isolated this code and re-ran this section without extrusion and surely enough I was able to reproduce it again, I had several people in out lab watch it no one has any clue where the problem is. The rail is clean and lubericsted. there are no irregular teeth on the belt, the belt is taught... and this seems issue seems independent of the slicer.

Baffled, I have come to the internet, I have arecorder the phenomenon here: https://youtu.be/dYjXroCMBmM

Please help me figure this out. This printer is in our research lab and I only have a limited time to install and use it this summer.

Thanks
Attachments
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IMG_7051.JPG
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Last edited by clayinmn on Thu Jun 25, 2015 7:07 pm, edited 1 time in total.

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ednisley
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Re: Atypical X-axis skipping problem (please help)

Post by ednisley » Thu Jun 25, 2015 6:37 pm

clayinmn wrote:It reproduced this skipping effect EACH LAYER during the return from home.
Most likely, the tiny setscrew holding the X axis pulley on the motor shaft is loose, which lets the pulley slap back and forth as the motor reverses. When and where it slaps around depends on the trajectory, which would explain everything you're seeing.

The screw should be centered on the flatted sector of the motor shaft, firmly tightened, and held in place with threadlocker. Remove the screw, apply threadlocker, reinstall, tighten firmly, done!

While you have the hood up, check the Y axis setscrew, too.

Of course, I may be completely wrong (again), but it's an easy thing to overlook and you've eliminated all the other common gotchas...

clayinmn
Posts: 4
Joined: Thu Jun 25, 2015 4:17 pm

Re: Atypical X-axis skipping problem (please help)

Post by clayinmn » Thu Jun 25, 2015 6:55 pm

Thanks for your reply,
ednisley wrote: Most likely, the tiny setscrew holding the X axis pulley on the motor shaft is loose, which lets the pulley slap back and forth as the motor reverses. When and where it slaps around depends on the trajectory, which would explain everything you're seeing.
I checked that when I tightened the belt, Just looked again and everything looked aligned and tight - but I realigned and tightened it again to make sure.. don't think it made a difference

Makergear Support just told me that It might be caused by Arduino IDE 1.6.4... So I am going to try 1.5.5 which is what they recommended and put on the wiki. I'm going to try that and report back.

clayinmn
Posts: 4
Joined: Thu Jun 25, 2015 4:17 pm

Re: Atypical X-axis skipping problem (please help)

Post by clayinmn » Thu Jun 25, 2015 7:06 pm

Well... uploading the firmware in Arduino IDE 1.5.5 seems to have worked... I guess I should have just done as the wiki said instead of going for the newest release

Issue fixed :D

Thanks!

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insta
Posts: 2007
Joined: Tue Sep 16, 2014 3:59 am

Re: Atypical X-axis skipping problem (please help)

Post by insta » Fri Jun 26, 2015 1:14 am

clayinmn wrote:Well... uploading the firmware in Arduino IDE 1.5.5 seems to have worked... I guess I should have just done as the wiki said instead of going for the newest release

Issue fixed :D

Thanks!
You don't want to know how mad I was when I found out the Arduino version itself was what was messing up my carefully tweaked custom firmware. WEEKS I spent with intermittently failing prints.
Custom 3D printing for you or your business -- quote [at] pingring.org

jsc
Posts: 1864
Joined: Thu Apr 10, 2014 4:00 am

Re: Atypical X-axis skipping problem (solved!)

Post by jsc » Fri Jun 26, 2015 4:33 pm

Has anyone informed either Arduino or the Marlin folk to ask them what is going on?

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